CH 4: Tissue level of organization

What are epithelial tissues: 1

large sheets of cells that cover surfaces of body (inner & outer)

Characteristics of epithelial tissues: 4

• has a lot of cells; will find mainly cells here

• Joined by junctions

• Has polarity: apical and basal surface

• Avascular and highly regenerative

3 types of cell junctions:

• Tight junctions: epithelial becomes a selective barrier; no extracellular space between them, movement through the extracellular space is blocked

• Gap junctions: facilitates movement of adjacent cells (passageway)

• Anchoring junctions: mechanical stability to tissues; desmosomes, hemidesmosomes, and adherends.

Functions of epithelial tissues: 5

• protect from physical, chemical, and biological damage:

  • UV radiation

  • Bacteria and viruses

  • Dirt and debris

  • Physical abrasion

Classification of epithelial tissue shapes:

• squamous= flat

• cuboidal= equal height and width

• columnar=tall

Goblet cells are found in where and do what

Location: pseudostratified ciliated columnar epithelium and simple columnar epithelium

• Found in small intestine

Function: secrete mucous

Simple squamous epithelium:

Location: alveoli of lungs, lining of heart, blood vessels, and lymphatic vessels

Function: facilitates absorption, diffusion, filtration; secretes lubricating substance.

Simple cuboidal epithelium:

Location: in ducts of secretory portions of small glands and kidney tubules

Function: facilitates filtration, secretes, and absorbs

Simple columnar epithelium: (2 types)

Ciliated simple columnar epithelium:

Location: uterine tubes, larger bronchioles, uterus

Function: absorbs and moves mucus and fluids

Non-ciliated columnar epithelium (with microvili):

Location: small intestine, bladder

Function: absorption and secretion

Pseudostratified Columnar epithelium: (2 types)

PCCE:

• Location: trachea, bronchi, and upper respiratory tract

• Function: secret mucus and move things along

Non-ciliated Pseudostratified Epithelium:

• Location: epididymis, vas deferens

• Function: secretion, absorption, protection

Stratified squamous epithelium: (2 types)

Keratinized Stratified squamous epithelium:

Location: skin, soles of feet, and palms of hands

Function: protect against abrasion

Non Keratinized Stratified squamous epithelium:

Location: esophagus, mouth and oral cavity, vag

Function: protects against abrasion

Stratified cuboidal epithelium:

Location: excretory ducts of glands: Sweat glands, salivary glands, mammary glands

Function: provides structural protection, and helps with secretion

Stratified columnar epithelium:

Location: male and female urethra

Function: secretes and protects

Transitional epithelium:

Location: lines bladder, urethra, and ureters

Function: allows for stretch and expansion; it is on surface of organ that needs to change size

What is Glandular epithelium:

• modified cells whose main purpose is to synthesize and secrete substances

What are the 2 types of glands:

• Exocrine glands: release substances into a duct that leads to surface

• Endocrine glands: release their substances (hormones) into blood stream or interstitial fluid

3 types of glandular secretion:

• Merocrine secretion: cell remains intact (think exocytosis)

• Apocrine secretion: apical portion of cell is released (pinched off portion of cell is secretion)

• Holocrine secretion: cell destroyed as it releases product; mature cell dies and becomes secretory product

Connective Tissue serves to…

• support and connect other tissues and lay down structures

Characteristics of connective tissues: 2

• cells are spread out within a matrix; matrix typically made of:

  • Ground substances (fluid, gel, hardness) and protein fibers (collagen, elastic, reticular)

Function of connective tissues: 5

• support

• connect/bind

• protect

• transport

• defend

Connective tissue proper has 2 types with subcategories:

Loose connective tissue:

• Areolar, adipose, reticular

Dense connective tissue:

• regular “elastic” and irregular “elastic”

Supportive connective tissue has 2 types with subcategories

Cartilage:

• Hyaline, elastic, fibrocartilage

Bone:

• compact bone and spongy bone

2 types of fluid connective tissue:

• Blood and lymph

True or false: fibroblasts are present in all connective tissue proper

True

What type of stem cell is a Mesenchymal cell?

• A multipotent adult stem cell

What is parenchyma:

• functional cells, blood vessels, and nerves of the organ

Dense Connective tissue: 3

Regular dense connective tissue: tendons and ligaments; oppose force in one direction; parallel fibers

Irregular dense connective tissue: dermis, shoulder capsule; oppose force in multiple directions

Elastic dense CT: wall of arteries

Loose Connective tissue:

Areolar: forms lamina proper of mucous membranes; supports epithelium, surrounds blood vessels

Reticular: form network for filtration; lymphatic organs (spleen, lymph nodes, liver)

Adipose: hypodermis, mammary glands, around kidneys; stores fat, insulation; few nuclei, complete connection

Supportive connective tissue: 2 types

Bone:

• Compact: osteons

• Spongy: trabeculae

Cartilage:

• Hyaline: lines articulating surfaces/joints, costal cartilage, nasal septum, tracheal rings; very glassy

• Elastic: ear, epiglottis; goes back to original shape

• Fibrocartilage: intervertebral disks, menisci, pubic symphysis, knees; resists compressive forces

True or false: Does cartilage have an avascular matrix

True

What is inside the lacunae of cartilage?

Chondrocytes

What are the 4 types of membranes:

Mucous membranes

Serous membranes

Cutaneous membranes

Synovial membranes

What is a membrane and what must it have to be considered one?

• Membranes are: physical barriers that line or cover portions of body

• It must consist of epithelium and AT LEAST one type of connective tissue

Mucous membranes: 4

Location: digestive, respiratory, urinary, and reproductive tracts

• line passageways with external connections

• epithelial surface must be moist to reduce friction and facilitate absorption and secretion

• the Lamina propria is areolar connective tissue

Serous membrane:

Location: pleura, pericardium, peritoneum

• line cavities NOT open to outside

• thin but VERY strong

• fluid transudate reduces friction

• typically double walled (parietal & visceral layer)

Cutaneous membrane:

Location: skin, exterior surface of body

• thick, waterproof and dry

Synovial membrane:

lack what?

Location: line articulating joint cavities

• produces synovial fluid (lube)

• protects ends of bones

• lacks a TRUE epithelium

3 characteristics of muscle tissue:

• excitable; responds to stimulus

• contractile; generate a pulling force

• allows for movement of and within the body

Skeletal muscle: histology, function, location

• long, cylindrical fibers, multiple peripherally located nuclei, striated

• voluntary movement, produces heat, protects organs

• attached to bones and around entrance points of body (mouth, anus)

Cardiac: histology, function, location

• uni/binucleated, intercalated disks, branches, short

• contracts to pump blood

• heart

Smooth muscle: histology, function, location

• uni-nucleated, no striped, spindle-shaped, short

• involuntary contraction

• walls of major organs and passageways